To use a normal torrent client:

In the life is feudal folder where you can find the launcher executable. There is a folder called tmp in that folder. This contains the torrent files that are being downloaded by the launcher including the temporary files.
You can put those torrent files into a normal torrent client and it will download them as normal.  Then either if your torrent client likes the temporary files of the launcher just point it at the temporary files. Or if it doesn't point it at new files and copy them back later.

The download is still excruciatingly slow. But it no longer ruins your upload if you limit the uploadspeed in the torrent client.